Built my first FFF project...an "STC" which is essentially a small Bird Dog with a 36" Wingspan. I put a Himax 2212-1180 outrunner on it and it's powered with a 2C 1200 etec lipo.

Now that I have the CG balanced correctly and have the right prop, it flies really great! perfectly straight and nice ROG's. It's prone to stalling if you apply too much power or try to make too tight a turn while going slow, but if you're careful with the sticks, it's a great 3ch scale flyer.

I'm very happy with this first build with FFF. I think the next project will be a 60" AP version of this plane.

I wonder if changing the thrust line of the motor would help with the stall-when-power-is-applied problem? My Decath RTF came so nose heavy, and with so much down-thrust that elevator trim needed to be positive just to keep the darn thing in the air... After fixing these problems it no longer stalls durring take off.

Because the wing has struts, it's kind of difficult to tell what the proper cg is. I'm going to get in touch with the designer and see what he says.

You have a good point about the thrust line. Right now it's level but I might have to adjust that down and to the right a bit and see what happens. I'll have to modify the stick mount to do that, but it's definitely worth a try.

Steve,
As far as the COG try 30% of the MAC If that is where it is now move it yo 28% or so. I have found that you can get a good flight at as little as 25% of the cord. Move it a little bit at a time and try it out. Good luck
Paul

It's flying nicely now. I think that because it's essentially overpowered by a brushless, the CG "moves" based on how much I'm on the throttle. Also when I constucted it, I used hot glue on the wing saddle which added weight and my servos are a bit more aft than then need to be. Otherwise, unless I want to add lead, I have nothing to shift forward to adjust the CG...the battery's as close to the nose as possible. At any rate, I was able to let it fly itself for about 10 minutes the other day while I took pictures. Dead calm. That doesn't happen very often!

The AUW is 11.5 oz so when I cut the throttle and set the elevator at about 75% up, it floats like a feather. Not bad for about $1.00 worth of foam!

If I build another one, I'll watch my construction techniques and give myself some options for adjusting CG. Using the small outrunner instead of the 350 brushed really makes a difference. Not sure if it's all good either.

Because the wing has struts, it's kind of difficult to tell what the proper cg is. I'm going to get in touch with the designer and see what he says.

You have a good point about the thrust line. Right now it's level but I might have to adjust that down and to the right a bit and see what happens. I'll have to modify the stick mount to do that, but it's definitely worth a try.

If this is Waterdog's "STC" the CG position is marked on the plan, at least it is on the plan I d/l'd and built mine from.